Moving between stable and development nightly build trees
To move between the stable (Fedora 28 based) and the development (Fedora 29/Rawhide based) OSTrees use the following procedures. The process outlines moving from stable to devel, to go the other way just substitute the Fedora release numbers.
Update the release key to the version you wish to move to:
sudo vi /etc/ostree/remotes.d/fedora-iot.conf
Rebase the OSTree:
sudo rpm-ostree rebase -b fedora/29/aarch64/iot